For example, in a construction machine such as a hydraulic excavator or a hydraulic crane, in order to prevent a work machine such as a boom or an attachment from interfering with a main body of the construction machine, a measure is taken of preventing the work machine from interfering with the main body by installing a distance measurement sensor onto the main body and sensing the distance between the main body and the work machine.
For example, Patent Literature 1 discloses an interference prevention device that uses a plurality of ultrasonic sensors to determine whether or not a bucket has entered an interference risk area set at the front of a cab.
However, with regard to interference prevention devices provided with distance measurement sensors, there is a problem such that a granular disturbance object, such as a rain drop or a snow particle, flying near a construction machine during rain or snow is erroneously detected as a work machine or a person approaching a main body, and the operator's work is interrupted due to an unnecessary warning being issued to the operator or the work machine being automatically stopped.
Further, Patent Literature 1 does not give any consideration to disturbance objects, and thus a situation in which a disturbance object is erroneously detected as a work machine cannot be prevented in Patent Literature 1.